Self-expandable stent systems for bifurcated lesions

ABSTRACT

Self-expandable bifurcation stent and systems for delivery and implantation of the self-expandable bifurcation stent, comprising a self-expandable bifurcation stent made of a material possessing shape memory, capable of shaping a mesh with cylindrical surface and marked by radioactive labels, and the delivery system for its implantation, comprising a polymeric tubular catheter with a cap at the distal end, a guiding wire and a pushing wire, where the tubular catheter is executed double-barreled, one lumen accommodating the guiding wire, and the second lumen accommodating the pushing wire with a cap at its distal end, which cap is executed in the shape of a polymeric elastic cap put over the tubular catheter accommodating, between the polymeric elastic cap and the tubular catheter, the stent in the first position with the reduced diameter, the cap is executed with the capability of distal  5  moving along the guiding wire and along the tubular catheter accommodating the stent, by means of the pushing wire, and with capability of unrolling the stent at the proximal end into the second position with greater diameter, and the capability of backwards proximal moving thus returning the stent to its first position in the tubular catheter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of PCT/RU2006/000494, filed onSep. 25, 2006, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

The invention relates to medical devices, namely to the devices appliedin endovascular surgery and interventional cardiology for recovery ofnarrowed bifurcated sections of a vessel lumen, in particular, in a sidebranch of the coronary arteries or in the carotid arteries bifurcation.

Fixing a stent in arteries in a bifurcated zone, especially in coronaryarteries, constitutes one of the main problems of endovascular surgeryand of interventional cardiology in particular. At the present moment,stent techniques, where a stent is implanted into the basic artery arerather common. An additional wire is introduced in a lateral branchthrough a mesh of the stent and the final angiographic result of theoperation is achieved after the balloon angioplasty of the bifurcatedzone by two “kissing” balloons. Stenting of bifurcated lesions ofarteries is also performed by two stents simultaneously (usingtechniques: such as cullotte, crush, V-stenting, T-stenting), whichrepresents a high risk of a damage of the arterial wall, a high risk ofrestenosis and intra-operational technical difficulties. Fulloptimization of the diameter of an artery in a bifurcated zone by usingconventional stents is a difficult problem. There are some designs ofspecial bifurcation stents (for example, the Multi-Link Frontier Stentfrom Guidant) where the technical result is achieved due to two balloonsand two wires on which the stents are clipped and which are positionedboth in the basic artery and in a lateral branch. Another type ofbifurcation stents has a special mesh structure which has the aperturefor a lateral branch (SLK-View™ stent, Advanced Stent Technologies),that allows optimizing implantation of the second stent in a lateralbranch. In clinical practice, a Nitinol bifurcation stent by AXXESSPlus, Devax, Inc. is commonly used. The stent is designed in the shapeof a frustum, thus, the basic advantage of this stent is the lowerprobability of shifting plaque masses in a lateral branch duringstenting the basic artery. At the same time, all bifurcation stents usedtoday in the clinical practice, have design which, to certain extent,ensures stenting the basic artery and reinforcement of an ostium of alateral branch, but they do not provide full covering along a lateralbranch. These stents have, as a rule, a rather complicated design andthe restricted spectrum of application.

From the Russian Patent RU2192810, a set of tools for transluminalinsertion of a tubular stent, including self-expandable tubular stentwhich serves as a transplant, and a device for introduction of thestent, are known. The tool set does not solve the problem of highprecision installation of the stent in an ostium of a lateral arterialbranch.

An eccentric stent for implantation in a lateral arterial branch isknown; it is expanded by means of a balloon catheter (see laid open U.S.Patent Publication No. 2004/0186560). The design of the above stent isadapted for implantation in an ostium segment of a lateral branch of acoronary artery. However, the system of radioactive labels used in thisdesign, does not provide for accurate positioning of the truncated partof the stent in the ostium of the arterial segment that can essentiallyreduce the safety standard of endovascular operations.

Another solution is presented in Russian patent RU2121317. In thissolution the self-recovering stent with delivery system for itsimplantation in the blood vessel, composing an implantation system,including self-expandable bifurcation stent marked by radioactive labelsand made of a wire shaping a cylindrical mesh which material has theshape memory, and the delivery system for implantation of theself-expandable bifurcation stent, containing a polymeric tubularcatheter with a polymeric cap at the distal end, a guiding wire and apushing wire, is described. Though this system has the orientationagents in the form of the radioactive labels located on the stent, theextremely close disposition of labels seriously hampers the accurateorientation by the clipped labels.

SUMMARY OF THE INVENTION

The claimed invention is intended at elimination of drawbacks listedabove.

The technical result achieved at use of the claimed system and thedevice, consists in the increased accuracy of positioning of a stent ina place of an arterial bifurcation or nearby such place, due to newdesign of the stent, having an oblique part, and due to the particularlocation of radioactive labels, and in providing a possibility of exactadjustment of the position of the stent during its implantation in abifurcated arterial segment due to new design of the stent deliverysystem.

The essence of the claimed invention consists in that a self-expandablebifurcation stent is formed in the shape of the constricted mesh made ofa material possessing shape memory and forming, at expansion, acylindrical surface, marked by radioactive labels, where, at theproximal end, the cylindrical surface of the stent is truncated, and theangle between the longitudinal axis of the stent and the plane of thecross-section, is within the range 30° to 70°, and the radioactivelabels are placed on the proximal end of the cylindrical surface of thestent, the first label is located at the end of the short element of thecylindrical surface, the second label is located at its longest element,and the third label is located opposite to the first label.

It is preferable, that the stent has been executed of Nitinol.

Besides, the first radioactive label can have diameter exceeding that ofthe second label or the third labels.

The mesh with the cylindrical surface can be covered, partially orentirely, by a polymer containing a drug.

Also the mesh with the cylindrical surface can be covered, partially orentirely, by a drug.

The self-expandable bifurcation stent delivery system contains apolymeric tubular catheter with a polymeric cap at the distal end, aguiding wire and a pushing wire, wherein the tubular catheter is formedas a double-channel (i.e., having two lumens or channels), one lumenaccommodating the guiding wire, and the second lumen accommodating thepushing wire, whose the distal end is attached to a polymeric capexecuted in the shape of a polymeric elastic cap put over the tubularcatheter, with capability of accommodating a stent in the space betweenthem, i.e., coaxially. The tubular catheter can be formed as adouble-channel in a distal part only, while the lumen for the guidingwire should be available along the whole length of the catheter.

The cap is formed with a capability of distal movement along the guidingwire and along the tubular catheter containing the stent inside, bymeans of the pushing wire.

Also, the cap has been formed with the capability of proximal movementalong the tubular catheter by means of the pushing wire, to its initialposition.

The lumens (channels) in the tubular catheter for movement of theguiding wire and the pushing wire have a diameter between 0.007 inchesto 0.02 inches.

The system for implantation of the self-expandable bifurcation stentcontains a self-expandable bifurcation stent made of a materialpossessing shape memory, capable of shaping a mesh with cylindricalsurface and supplied with radioactive labels, and the delivery systemfor its implantation, containing a polymeric tubular catheter with a capat the distal end, a guiding wire and a pushing wire. The tubularcatheter is formed as a double-channel, one lumen accommodating theguiding wire, and the second lumen accommodating the pushing wire with apolymeric cap at its distal end. The cap is formed in the shape of apolymeric elastic cap put over the tubular catheter with the capabilityof accommodating, between the tubular catheter and the polymeric cap,the stent in the first position, i.e., with the reduced diameter, thecap is formed with the capability of distal moving along the guidingwire and along the tubular catheter accommodating the stent, by means ofthe pushing wire, and with capability of unrolling the stent at theproximal end into the second position, i.e., with greater diameter, andthe backwards proximal moving with the capability of returning the stentin its first position in the tubular catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the general view of system for implantation of aself-expandable bifurcation stent.

FIG. 2 shows various stages of insertion and remission of a stent at itsimplantation in the chosen place of a blood vessel.

FIG. 3 shows stages of the stent implantation in the ostium of anartery.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Self-expandable bifurcation stent 1 (FIG. 1, view 1.1) is made of amaterial possessing shape memory (for example, Nitinol), capable ofshaping a mesh with cylindrical surface. Its cross-section in unrolled,i. e. the second, position, is shown at FIG. 2 (view 2.1), wherein thecylindrical surface of the stent, at the proximal part, is truncated bycross-section 5, and the angle a between the longitudinal axis of thestent and the plane of cross-section 5 is within the range 30° to 70° .The cylindrical surface of the stent contains radioactive labels 6located at the proximal end of the cylindrical surface of the stent inthe mesh points, the first label is located at the end of the shortelement 3 of the cylindrical surface, the second label is located at theend of the long element 4, and the third label is located on the longelement 4 in front of the first label.

The first radioactive label can have the diameter in excess of that ofthe second or the third labels. Such disposition of labels allowsprecise positioning of the stent in the ostium segment of an arteryduring partial shift of a polymeric cap and partial unrolling of adistal part of the stent, and during divergence of labels, is sufficientfor precise visualization of the stent position. Also, the mesh withcylindrical surface may be covered, partially or entirely, with apolymer containing drug, or with a drug directly, thus reducing the riskof restenosis in a place of the stent implantation.

The delivery system for implantation of a self-expandable bifurcationstent comprises a polymeric tubular catheter 10 (see FIGS. 1 and 2) withcap 7 at the distal end, a guiding wire 9 and the pushing wire 8, wheretubular catheter 10 is formed as a double-channel (see cross-section onFIG. 1, view 1.2), the first lumen 91 of which accommodates guiding wire9, and the second lumen 81 accommodates pushing wire 8 the distal end ofwhich is affixed to cap 7 executed in the shape of a polymeric elasticcap, put over tubular catheter 10 with the capability of accommodatingstent 1 between them, such that in the rolled-up position, the stent 1is covered entirely by the polymeric cap 7, whose tip is completelyclosed.

Cap 7 is formed with the capability of distal moving along guiding wire9 and, accordingly, along tubular catheter 10 accommodating stent 1, bymeans of pushing wire 8. At the same time, cap 7 is formed withcapability of proximal moving along tubular catheter 10 to its initialposition by means of pushing wire 8. It is preferable, that the lumensfor the guiding wire and the pushing wire in the tubular catheter hadthe diameter of 0.007 to 0.02 inches.

Delivery system and the bifurcation stent (FIG. 2.1) form a system forimplantation of self-expandable bifurcation stent, which works asfollows: The guiding wire 9 is introduced into a lateral branch of thebasic artery, and along the wire a the self-expandable stent system,i.e., catheter 10, containing stent 1 in the rolled-up position (i.e.,with the reduced diameter) (FIG. 2, view 2), is then introduced. Bymeans of pushing wire 8, cap 7 executed in the shape of a polymericelastic cap and put over tubular catheter 10, is moved to the distaldirection along the branch of the vessel (see FIG. 3, view 3.1), alongthe guiding wire 9 and along tubular catheter 10 (in the first and inthe second lumens of the catheter), thus releasing the proximal part ofstent 1.

At this stage the proximal part of stent 1 is unrolled in the secondposition, i.e., with a larger (expanded) diameter (see FIG. 2, view2.3), and the first and the second radioactive labels 6 should coincidewith the proximal end of the stented section (FIG. 3, view 3.2), thethird label is located opposite to the first one and, due to largerdiameter of the proximal part of stent 1, enables more precisepositioning of the stent in the ostium of an artery, for example, byrotating the catheter, the oblique part of which will be thus placed inthe correct position.

In case where the exact placement of the stent requires its rotationalong the longitudinal axis or movement along the vessel, the cap 7 ismoved in the proximal direction, and the stent returns to its firstposition with the reduced diameter.

After adjustment of the exact position of the stent, the cap 7, by beingmoved to the distal direction, completely releases the stent (FIG. 2,view 2.4 and FIG. 3, view 3.3), which restores its cylindrical shapewith the oblique proximal end in the ostium of the artery, and the cap,together with the catheter, can be removed by moving to proximaldirection (FIG. 3, view 3.4).

The claimed design provides for high reliability and precision ininstalling the stent in an ostium of an artery that essentially reducesprocedure risk resulting from the non-optimum implantation of the stent.

1-13. (canceled)
 14. A self-expandable bifurcated stent, comprising: aconstricted mesh made of a material possessing shape memory and forming,at expansion, a cylindrical surface marked by radioactive labels; themesh having, at a proximal end, a cylindrical surface that is truncated;wherein an angle between a longitudinal axis of the stent and a plane ofthe cross-section between 30 degrees and 70 degrees; at least threeradioactive labels placed at the proximal end of the cylindricalsurface, the first label being located at an end of a short element ofthe cylindrical surface; the second label being located at an end of along element of the cylindrical surface; and the third label beinglocated opposite the first label.
 15. The stent of claim 13, wherein thestent is made of Nitinol.
 16. The stent of claim 13, wherein the stentis made of material possessing shape memory.
 17. The stent of claim 13,wherein the first radioactive label has the diameter larger thandiameters of the second label and the third label.
 18. The stent ofclaim 13, wherein the mesh with the cylindrical surface is, partiallycovered by a polymer containing a drug.
 19. The stent of claim 13,wherein the mesh with the cylindrical surface is, completely covered bya polymer containing a drug.
 20. The stent of claim 13, wherein the meshwith the cylindrical surface is, partially covered by a drug.
 21. Thestent of claim 13, wherein the mesh with the cylindrical surface is,completely covered by a drug.
 22. A delivery system for implantation ofself-expandable bifurcation stent, the delivery system comprising: apolymeric tubular catheter having a polymeric cap at its distal end; aguide wire; a pushing wire; at least two channels formed in thepolymeric tubular catheter, the first channel accommodating the guidewire, and the second lumen accommodating the pushing wire which distalend is attached to a polymeric cap formed in a shape of a polymericelastic cap over the tubular catheter and capable of accommodating astent between them.
 23. The system of claim 22, wherein the tubularcatheter is formed with two channels in its distal part only and thechannel for the guide wire is formed along an entire length of thecatheter.
 24. The system of claim 22, wherein the cap is formed with acapability of distal movement along the guide wire and along the tubularcatheter having the stent inside, by means of the pushing wire.
 25. Thesystem of claim 22, wherein the cap is formed with the capability ofproximal movement along the tubular catheter to its initial position bymeans of the pushing wire.
 26. The system of claim 22, wherein thechannels in the tubular catheter for movement of the guide wire and thepushing wire have diameters between 0.007 inches to 0.02 inches.
 27. Asystem for implantation of the self-expandable bifurcation stent,comprising: a self-expandable bifurcation stent made of a materialpossessing shape memory, capable of shaping a mesh with a cylindricalsurface and marked by radioactive labels; and a delivery system forimplantation of the stent, the delivery system comprising a polymerictubular catheter with a cap at the distal end, a guide wire and apushing wire, wherein the tubular catheter is formed with two channels,one channel accommodating the guide wire, and the second channelaccommodating the pushing wire with a cap at its distal end, wherein thecap is formed in the shape of a polymeric elastic cap over the tubularcatheter such that the stent is accommodated between the polymericelastic cap and the tubular catheter, the stent in a first position witha reduced diameter, and wherein the cap is capable of distal movingalong the guide wire and along the tubular catheter, by means of thepushing wire, and wherein the cap is capable of unfolding the stent atthe proximal end into the second position with greater diameter, andwherein the cap is capable of backwards proximal movement to return thestent to the first position in the tubular catheter.